How to Install a Basic Stormwater Drainage System at Home

March 6, 2025

A basic stormwater drain is just a way of catching water where it sits and giving it a pipe with a steady fall to somewhere it's allowed to go. Most backyard flooding comes down to water that has nowhere to run, so the planning matters a lot more than the digging, and it's worth getting the planning right before you buy a single length of pipe.

Watch where the water goes first

Next time it rains properly, go outside and watch it. Note where it pools and where it's coming from, because a downpipe or a path that runs the wrong way is often the real cause, and find the lowest point of the yard while you're out there. A lot of drainage problems turn out to be a downpipe that's come apart underground, and the post linked below on repairing a broken stormwater pipe covers that one.

Work out where it's allowed to go

The water has to end up at a proper discharge point, which on most house blocks is the street kerb or an existing stormwater line, and it can't be sent onto a neighbour's property. If you're not sure where yours is, or you want to connect into the kerb or a council drain, check with your council before you dig, because the rules on connections vary.

Keep it well away from the house as well. A lot of soil around here is reactive clay that swells when it's wet and shrinks when it dries, so a soggy patch against the footings can move the house, and that's exactly the problem you're trying to fix.

Pick the right kind of drain

If the water arrives on the surface, at the bottom of a path or in front of a door, a grated inlet or a channel drain catches it and sends it away through solid PVC stormwater pipe. If the ground itself stays soggy, a gravel trench works better, with slotted agricultural pipe lying in gravel and the whole trench lined with geotextile fabric so soil doesn't wash in and block it.

Set the fall before you dig

Water only moves if the pipe runs downhill the whole way, and a fall of about 1 in 100, which is 10mm for every metre, is the minimum I'd aim for. Run a string line from the inlet to the outlet and set it to the fall you want with a line level on it. Then measure down from the string as you dig so the bottom of the trench follows it.

Before you start digging, get the underground services located, because gas, water, power and phone lines all run through backyards and a spade finds them the hard way.

Lay it and join it

Dig the trench to the line and take any rocks out of the bottom, because the pipe needs to sit evenly along its length rather than rest on high spots. For solid PVC stormwater pipe, every joint gets primed and then glued with solvent cement, and the pipe goes together within a minute or so of the glue going on. Bends should be gentle rather than tight 90 degree turns where you can avoid them, because leaves and silt collect in a sharp corner.

Run water through it before you backfill. If it comes out the far end at a steady flow and nothing pools in the trench, cover it up.

Keep it running

Clear the grates after storms and when the leaves come down, and flush the line with a hose every so often. A drain that floods again after a year is nearly always a blocked inlet rather than a broken pipe.

Shop related products

Plumma's Red Priming Fluid PVC Pipe Primer, 250ml. Cleans and softens the pipe before gluing.
Plumma's Blue Glue Type N PVC Solvent Cement, 250ml. Glues the stormwater joints together.
Supercraft Line Level. Sits on the string so you can set the fall.
Bricklayers Line, 100 Metre. The string line for marking the trench.

Did you know we also stock 90mm and 75mm PVC stormwater pipe in the shop, sold by the length or by the metre, along with the bends, junctions, couplings, grates and a channel drain with a galvanised grate. Non-woven geotextile fabric is sold by the metre too. They aren't on the website, so give us a ring on (08) 8536 4333 to check stock before you come in.

The online plumbing range is in plumbing.